The United States and the European Economic Community failed yesterday to reach an agreement that would hold off stiff penalties against European steel makers, but both sides said they would continue negotiations soon to solve their dispute over steel exports.

The Europeans' Council of Ministers meeting in Brussels proposed that the United States and European nations hold negotiations on steel exports and that U.S. punitive duties be delayed. Late yesterday U.S. officials agreed to the talks, but said the process of imposing duties to offset subsidies by European steel-producing nations would continue.

The Commerce Department, which issued a preliminary ruling last month that European governments unfairly subsidized steel exports to the United States by as much as 40 percent, required them to post cash or bonds in the amount of the subsidies pending a final ruling Aug. 24. At that time the duties--some as high as $250 a ton--could be made permanent.

Last week the economic community proposed slashing steel exports to the United States from four member countries by 10 percent until 1985 if the Reagan administration suspended investigations of steel imports. Commerce Secretary Malcolm Baldrige rejected that plan Thursday.

The EEC yesterday rejected a U.S. counterproposal to slash exports to the United States from all the offending countries to 20 percent below their average 1979-to-1981 level, the Commerce Department said.

The EEC Council of Ministers, after failing to come up with a steel export arrangement acceptable to U.S. officials, gave an EEC commission an "exclusive mandate" yesterday to solve the steel problem, the Commerce Department said.

"I hope and believe the continued good faith effort on both sides can result in a fair and amicable settlement that will relieve the injury caused to the U.S. steel industry . . . ," Commerce Undersecretary Lionel Olmer said.

If an agreement had been reached yesterday, Baldrige could have suspended the U.S. steel cases. However, any agreement reached now must be approved by the U.S. steel makers, who would have to withdraw their complaints.

Olmer said that rather than pursue the route of suspending the cases, both sides decided to continue discussing the steel-trade problem "in its entirety."